1. Field of the Invention
The present invention relates to a rotary electric machine capable of suppressing an energy loss due to induction or induced current by improving teeth of a stator and also relates to an electric wheelchair (or electrically powered wheelchair) mounted with such rotary electric machine.
2. Related Art
In a known art, as such a rotary electric machine, there has been provided an axial gap type rotary electric machine as shown, for example, in FIGS. 16 to 19.
Referring to FIGS. 16 to 19, the rotary electric machine is provided with a stator 3 formed with teeth 2 and a rotor provided with a plurality of magnets (permanent magnets), not shown, in which the stator and the rotor are arranged with a gap in a rotation axis direction.
More in detail, the each tooth 2 is composed of a plurality of steel plates 2a laminated in a radial direction thereof for a countermeasure to core loss, and a plurality of such teeth 2 are arranged and fixed side by side with a predetermined distance in the circumferential direction of a disc, i.e., substantially ring-shaped, stator yoke core 6. Coils are wound up around these teeth 2 through insulating material as bobbins, not shown. Further, as shown in FIG. 17, the teeth 2, the stator yoke core 6 and the coils are integrally fixed by means of molding resin 7 as shown in FIG. 16 such that surfaces 2b of the teeth 2 opposing to the rotor are exposed.
The steel plates 2a of the teeth 2 are assembled to the stator yoke core 6 in a separated state and then molded and fixed together by means of molding resin 7.
However, in such arrangement, it was troublesome to assemble the separated steel plates 2a, which involved cost increasing, thus being disadvantageous.
Because of such reason, in order to reduce troublesome working or loss in assembling, the respective steel plates 2a have been preliminarily fixed by caulking means, for example, such as half pierce member or like. Such structure is for example disclosed in Japanese Patent Laid-open (KOKAI) Publication HEI 11-318059.
This publication shows salient-pole type core lamination plates corresponding to the steel plates of the teeth mentioned above, the core lamination plates being laminated and fixed by means of a hole formed to the respective plates. Moreover, at the paragraph [0015] of this publication, there is a disclosure such that the holes are formed by punching process, and at the paragraph [0014], the punched-out plates are figured at a portion above the figure of a rolled steel plate in the respective pressing stage in FIG. 2. According to such description, it is apparent that the holes formed to the core lamination plates are through holes.
However, in the case where the respective steel plates 2a are fixed by using the half pierce member, when the fixing is made only at one portion, there is a fear of being separated during its assembling process because of no sufficient strength. For this reason, in order to achieve sufficient calking strength, it becomes necessary to calk the respective steel plates 2a at plural positions.
In addition, although these steel plates 2a are insulated by insulating films, such insulating films may be broken by the formation of the half pierce member, which may result in short-circuiting, and the respective steel plates 2a become electrically connected state. Accordingly, if such half pierce members are located at several portions, a closed circuit will be presented through these half pierce members, and a magnetic flux crosses this closed circuit and then the induction current passes, resulting in the cause of energy loss, thus being inconvenient and disadvantageous.
It has been therefore required to accept either one of conditions of (1) cost-up in assembling for achieving high efficiency (reduction of induction current loss) without forming the half pierce member or (2) efficiency-down for the reduction of cost.
Further, the holes for fixing the respective core lamination plates corresponding to the steel plates of the teeth (tooth) are formed in the above prior art publication, but these holes are through holes, which are not for causing the induction current.